import java.util.Arrays;
import java.util.Scanner;

public class HJ34 {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        while(sc.hasNext()){
            String str = sc.nextLine();
            char[] ch = str.toCharArray();
            Arrays.sort(ch);
            System.out.println(ch);
        }
    }
}
